[quote=@Lizmichi]
<Snipped quote by Stale Pizza>

Well, Neo did say we're going with Gen 6 moves so maybe we're going with HeartGold/SoulSilver. *shrug*
[/quote]

It's sort of because Ghost-type Pokemon were hardly worked upon before Gen III. Only on Gen IV and V did they pretty much double the size of that category and do some buffs and nerfs. Three-quarters of Ghost-type Pokemon exist in Sinnoh and Unova. :P

They haven't worked much with the Ice-type Pokemon, either.